Many illumination applications (e.g., luminaires) require control of the light attributes (e.g., direction or intensity) for both functional and aesthetic purposes. For example, in a workroom, high-intensity light may be directed toward one or more specific work areas, while the room is illuminated diffusely. Likewise, in a conference room, light may be directed toward the table area, while diffuse, ambient light illuminates the rest of the room.
Beyond the need to provide both directional and ambient/diffuse light, Applicants recognize the need to provide ambient light along with directional light to reduce glare. Specifically, a luminaire having high-intensity light can cause glare, owing to the stark contrast between the luminaire's high intensity light-emitting surface and the surface surrounding it. Applicants also recognize that glare from high-intensity light can be diminished by surrounding the high-intensity light-emitting surface with diffuse light, thereby reducing the aforementioned contrast.
Traditional approaches for providing both directional and diffuse light generally involve independently illuminating the directional and diffuse light-emitting surfaces. Often this is embodied in two or more different luminaires. This necessarily requires discrete lighting sources and driving circuitry, thus adding complexity and cost to the lighting system. Other applications involve halogen lamps, which may be configured to emit diffuse light backward for aesthetic purposes. However, halogen lamps tend to be inefficient (e.g., about 10-20 lumens/W or about 5% of theoretical light-generation efficiency), and, thus are not cost effective to operate.
Therefore, Applicants have identified a need for a luminaire that provides both directional and diffuse light in a single luminaire using efficient LED light sources, but avoids the complexity and cost of conventional lighting systems. The present invention fulfills this need, among others.